Seismic tremor location of 10 large paroxysmal eruptions of Tungurahua volcano, Ecuador

Abstract

SUMMARY The most recent eruptive period of Tungurahua volcano lasted 17 yr (1999–2016), generating strong eruptive phases with the release of large amounts of seismic and acoustic energies. We have selected 10 large eruptions and located their seismic sources. The location method involves applying a new method for correcting for site effects in the seismic records and identifying, in the frequency domain, the signals from the ground-coupled airwaves and pyroclastic flows. The locations are computed by minimizing the differences of the source energy rates in the [0.4, 2.5] Hz range. The results suggest that the first three eruptions have locations mainly concentrated at the [−1, 2] km depth range (asl), and the locations of the fourth eruption are mainly coincident with depths of a possible reservoir estimated from petrological studies. This fact strongly suggests that this eruption was responsible of changes in the dynamics of Tungurahua, making the volcano prone to produce Vulcanian eruptions.